comparing schedules to events for clashes

Hi guys! i was wondering if anyone could help me out...i've recently been put in charge of an organisation of about 150 people, and im in charge of making sure they are at events. I am wondering if there is a way, possibly the COUNTIF formula?! that would allow me to put every members schedule in, and then by typing in the weekday and time of the event, seeing if they have a clash? without having to go through each missing persons schedule? for example, if i had it written that say andrew has class on monday at 6 pm, if i then put in that there was an event on monday at 6 pm, is there a way that it will show me what people have a clash?

I hope what i need help with makes sense!

Thank you
Rosie